Hyaenodon
| image = Hyaenodon horridus, Niobrara County, Wyoming, USA, Late Oligocene - Royal Ontario Museum - DSC00114.JPG | image_caption = H. horridus, Royal Ontario Museum | image_width = 240px | regnum = Animalia | phylum = Chordata | classis = Mammalia | ordo = †Hyaenodonta | familia = †Hyaenodontidae | genus = †''Hyaenodon'' | type_species = †''Hyaenodon leptorhynchus'' | type_species_authority = Laizer and Parieu, 1838 | subdivision_ranks = Referred species | subdivision = *†''Hyaenodon andrewsi'' *†''Hyaenodon brevirostris'' *†''Hyaenodon chunkhtensis'' *†''Hyaenodon crucians'' *†''Hyaenodon filholi'' *†''Hyaenodon gigas'' *†''Hyaenodon horridus'' *†''Hyaenodon incertus'' *†''Hyaenodon leptorhynchus'' *†''Hyaenodon matthewi'' *†''Hyaenodon megaloides'' *†''Hyaenodon microdon'' *†''Hyaenodon mongoliensis'' *†''Hyaenodon montanus'' *†''Hyaenodon mustelinus'' *†''Hyaenodon pilgrimi'' *†''Hyaenodon raineyi'' *†''Hyaenodon venturae'' *†''Hyaenodon vetus'' *†''Hyaenodon weilini'' *†''Hyaenodon yuanchensis'' }} Hyaenodon ("hyena-tooth") is the type genus of the Hyaenodontidae, a family of extinct carnivorous fossil mammals from Eurasia, North America, and Africa, with species existing temporally from the Eocene until the middle Miocene, existing for about .[http://paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=40917&is_real_user=1 PaleoBiology Database: Hyaenodon, basic info] The various species of Hyaenodon competed with each other and with other hyaenodont genera (including Sinopa, Dissopsalis, and Hyainailurus), and played important roles as predators in ecological communities as late as the Miocene in Africa and Asia and preyed on a variety of prey species such as primitive horses like Mesohippus and early camels.Wang, Xiaoming; and Tedford, Richard H. Dogs: Their Fossil Relatives and Evolutionary History. New York: Columbia University Press, 2008.p17 Species of Hyaenodon have been shown to have successfully preyed on other large carnivores of their time, including a nimravid ("false sabertooth cat"), according to analysis of tooth puncture marks on a fossil Dinictis skull found in North Dakota.Hoganson, John W; and Person, Jeff. "Tooth puncture marks on a 30 million year old Dinictis skull." Geo News. July 2011. p12-17. Description , around 1920|alt=|300x300px]] Some species of this genus were among the largest terrestrial carnivorous mammals of their time; others were only of the size of a marten. Remains of many species are known from North America, Europe, and Asia.Wang, Xiaoming, Qiu, Zhanxiang, and Wang, Banyue, 2005. Hyaenodonts and Carnivorans from the Early Oligocene to Early Miocene of Xianshuihe Formation, Lanzhou Basin, Gansu Province, China, Palaeontologia Electronica Vol. 8, Issue 1; 6A: 14p, online Typical of early carnivorous mammals, individuals of Hyaenodon had a very massive skull, but only a small brain. The skull is long with a narrow snout - much larger in relation to the length of the skull than in canine carnivores, for instance. The neck was shorter than the skull, while the body was long and robust and terminated in a long tail. The average weight of adult or subadult H. horridus, the largest North American species, is estimated to about and may not have exceeded . H. gigas, the largest Hyaenodon species, was much larger, being and around .WANG X. & TEDFORD R. H. 2008. — Dogs, their fossil relatives and evolutionary history. Columbia University Press: 1-219. H. crucians from the early Oligocene of North America is estimated to only . H. microdon and H. mustelinus from the late Eocene of North America were even smaller and weighed probably about .Naoko Egi (2001) Body Mass Estimates in Extinct Mammals from Limb Bone Dimensions: the Case of North American Hyaenodontids _Palaeontology 44 (3) , 497–528 Compared to the generally larger (but closely related) Hyainailouros, the dentition of Hyaenodon was geared more towards shearing meat and less towards bone crushing. Tooth eruption Studies on juvenile Hyaenodon specimens show that the animal had a very unusual system of tooth replacement. Juveniles took about 3–4 years to complete the final stage of eruption, implying a long adolescent phase. In North American forms, the first upper premolar erupts before the first upper molar, while European forms show an earlier eruption of the first upper molar.Katharina Anna Bastl, First evidence of the tooth eruption sequence of the upper jaw in Hyaenodon (Hyaenodontidae, Mammalia) and new information on the ontogenetic development of its dentition, Paläontologische Zeitschrift (Impact Factor: 1.1). 10/2013; 88:481-494. DOI: 10.1007/s12542-013-0207-z Range and species |alt=|400x400px]] In North America the last ''Hyaenodon, in the form of H. brevirostris, disappeared in the late Oligocene. In Europe, they had already vanished earlier in the Oligocene. See also References Category:Hyaenodonts Category:Eocene mammals Category:Oligocene mammals Category:Miocene mammals Category:Miocene genus extinctions Category:Cenozoic mammals of Asia Category:Cenozoic mammals of North America Category:Cenozoic mammals of Africa Category:Cenozoic mammals of Europe Category:White River Fauna Category:Eocene genus first appearances Category:Prehistoric mammal genera Category:Fossil taxa described in 1838